The present invention relates generally to an apparatus and method for bonding a small, heat sensitive component onto another surface and, more particularly, for bonding heat sensitive chips to a base or substrate utilizing a current-pulsed, shaped resistive heating element to provide localized heating to a thermally setting thin film agent at the bond interface.
In magnetic recording technology, as well as in other technologies generally related to integrated circuit chips and other electronic components, it is often desired to accurately align and bond small components in a controlled and repeatable fashion both in research and manufacturing environments. Often, while one or more critical components may be severely damaged by the high temperature required by most conventional bonding methods, a lower temperature bond may not provide sufficient strength and stability and thus be unacceptable due to creep and delamination generally associated with such low temperature bonds.
It is known in the art to provide localized heating of a heat sensitive bonding agent by direct resistance heating utilizing an interface heater layer or element of a conductive material such as a thin metallic tape or a thick-film conductive paste. For example, published United Kingdom patent application no. 2127740A to Wolfson discloses a method for hermetically sealing a ceramic cover to a ceramic package or housing utilizing a high temperature vitreous sealant without excessively heating the electronic circuits and components therein. A heater layer of electrically conductive material is bonded to the sealing area of the ceramic package, for example. A layer of sealant material is applied over the heater layer and the package cover, for example, is then pressed against the package aligning the sealing area of the cover with the heater and sealant layers while an electric current is applied to the heater layer, causing the sealant material to bond to the heater layer thus bonding the cover to the package. To concentrate the thermal energy at the bonding area and minimize heating of components mounted within the package, portions of the package are comprised of ceramic material having a relatively low degree of thermal conductivity. Since it is also a necessary function of the package to conduct heat away from the electronic components therein, other portions of the package are necessarily comprised of a ceramic material having a high degree of thermal conductivity. While Wolfson effectively minimizes adverse heating of components mounted therein, at least two different ceramic materials having differing degrees of thermal conductivity are required for the package, thus increasing the complexity and expense of the package fabrication. Additionally, while most components within the package of Wolfson are mounted relatively large distances from the package sealing areas, critical components mounted at or in close proximity to the bonding site will not be thermally protected.